Add account migration UI (#11846)

Fix #10736

- Change data export to be available for non-functional accounts
- Change non-functional accounts to include redirecting accounts

app/workers/activitypub/move_distribution_worker.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+class ActivityPub::MoveDistributionWorker
+  include Sidekiq::Worker
+  include Payloadable
+
+  sidekiq_options queue: 'push'
+
+  def perform(migration_id)
+    @migration = AccountMigration.find(migration_id)
+
+    ActivityPub::DeliveryWorker.push_bulk(inboxes) do |inbox_url|
+      [signed_payload, @account.id, inbox_url]
+    end
+
+    ActivityPub::DeliveryWorker.push_bulk(Relay.enabled.pluck(:inbox_url)) do |inbox_url|
+      [signed_payload, @account.id, inbox_url]
+    end
+  rescue ActiveRecord::RecordNotFound
+    true
+  end
+
+  private
+
+  def inboxes
+    @inboxes ||= @migration.account.followers.inboxes
+  end
+
+  def signed_payload
+    @signed_payload ||= Oj.dump(serialize_payload(@migration, ActivityPub::MoveSerializer, signer: @account))
+  end
+end